Jacketed strip-wound metal hose



Jan. 15, 1963 B. NICHOLS JACKETED STRIP-WOUND METAL HOSE Original Filed Feb. 5, 1959 INVENTOR Lyman B. Nichols BY N, (QM AT ORNEY/7 htates atent truding the jacket by itself, in the form of a tubing which 3,073,351 in the unstressed condition has an inside diameter slightly JACKETED STRIP-WOUND METAL HQSE less than the outside diameter of the metal hose. A

Lyman p Watertown Conn" t length of such jacket tubing is then expanded by applying ggggz i Brass Company a corporation of 5 air pressure to its interior, and the metal hose is fed into Original application Feb. 5, 1959, Ser. No. 792,251, now the h expanded P s tubeh n, Whcn the air pres- Patent No. 3,015,133, dated Jan. 2, 1962. Divided sure is released, the acket tube contracts and hugs the and this application Apr. 7, 1961, Ser. No. 101,497 metal hose tightly. Apart from the awkward and labori- ZClaims. (Cl. 138-431) ous character of this procedure, it suflers from the disadvantages that only limited lengths of hose can be This invention relates to jacketed strip-wound metal j k by i use. d h h j k (unless bi i h more particularly, fleXible metal hose ably loose) is under substantial hoop stress. the strip-wound type havi g v21 Jacket 015 Plastlc fhateflal The hose of the invention is made by applying a plastic does not wrinkle appreciably when the 11056 18 btllllljacket t0 3 strip-wound interlocked (or square locked) This application is adivisioh 0f y copehdihg PP metal hose by an extrusion operation. As indicated Se ial No. 792,251, filed Fe r y 5, 1959 Whlch Issued above, such hose is formed of interlocking helical conon Jan ary 1962, as Patent Numhsl 3,015,133- volutions in which each convolution is movable relative In accordance With the invention, a thefmoplasfih to adjoining convolutions axially of the hose through the equivalent lackeiing material is extruded about the p interlock between a first position in which adjoining con wound hose while its convolutions are maintained fully 20 volutions are in direct contact with one another, with the Closed y the application of a Pushing force Which interstices between them fully closed, and a second posi vances it through the extrusion operation. Jacketed hose i i hi h dj i i convolutions are Spaced a b- Produced thsfeby is Characterized y having snugly stantial distance apart, with substantial interstices or fitting jacket which, however, is free from any noticeable ll spaces b t th Th new ho i ad by hoop stress when the hose is n t und h in 0f subjecting it to an axial force in a direction to maintain a tensile films, and which is further characterized y the convolutions in said first position while maintaining plete freedom of interpenetration of the jacket materi the axis of the hose substantially straight, and advancing into the spaces between adjacent convolutions of the hose. th hose by the application of a pushing force thereto Owing to the manner i which the new jacketed h is while maintaining its axis straight and with its-convolumade, bending of a straight length of the hose s accomtions in said first position. A jacket of plastic material panied by movement of adjacent convolutions only in a which is elastic when set then is extruded about the hose. direction away from each other on the outside Of the as it is being thus advanced, The linear velocity atwhich bend. There can be no movement of the convolutions tothe plastic jacket material is extruded is less than the ward each other on the insidecf the bend," and conselinear velocity at which the metal hose is advanced by quently wrinkling of the jacket on the inside of the bend the pushing force, so as to cause the fresly-extruded does not occur. V 5 plastic jacket to be'stretched and necked down into close Flexible metal hose of the strip-wound type is made by engagement with the outer surface-of thehose without winding a metal strip about a mandrel-and folding the penetrating 'between the convolutions =th e reof.- As av strip longitudinally so that the edge portions of eachcon- 40 result of this method of applying-the jacket, when the voluti'on ,of the strip overlap and form a locked seam with jacketed hose is bent adjacentfconvolutions can move only the preceding and succeeding convolutions. The flexiaway from each other on the outside convex side) of the f bility of metal hose made in this fashion'results from a .bend and not toward each otherion' the inside i(concav: limited freedom-of each hose convolution to be'displaced side) of theibendg and thereforewri'nklin'g of thejacket v axially through the interlock with respect to adjacentcondue to moverneritof the convolutions toward feach other-' volutions. When thenhose is bent,'thespa'cesbetweenon the inside of the bend is prevented; convolutions open slightly on the convex side of the bend, Closure of the convolutions, preparatory to pushing and j-close (or remain closed) on the .concave side. the metal hose'through the extrusion zone, is preferably For many purposes it is desirable to" apply a seamless effected by pushing the hose at a first linear .velocity jacket of flexible; plastic-material to the outer surface of through the extrusion zone, and advancing the hosefto' strip-wound'hose, to render it moisture tight, to protect the point of application-of the pushing force at a second the metal from abrasion, etc. The most convenient way linear" velocity which is substantially greaterthan said i. K of applying such jacket is to eX-trude it on a conventional first linear velocity, the difference between these firstplastic extruding machine. Conventional extrusion" ap and second linear velocities being 'greatenough to bring t nd procedures do not yield whollysatisfactory each convolutionoffthe hose into contact with adjoin-Q results, however, because the freshly extrudedjacket mate ing convolutions,.so .that njo further shortening of thewrial penetrates into the spaces between rthevconvolutions; f hose,,can -0ccur, and bending of thehoseicanoccurfonly j of the hose as the latter is drawn through the extrusion x by. movement of adjacent convolutionsawaysfroni' each apparatus. Asa result, flexibility ofthehose is impaired; otherlon thevoutside of the bend.- t T V "Moreover, when the resulting hose is bent, the convolu- .30 h6 d d Plas i at ial, which is advantageously be' rlfin dcauselunsightly and othepwise objectionablewrinkling-of;-theljacket. When it"isattempted tonun mjze penetration "of the jacket material in the spacs tween :conjvolutions' by extrudingthe jacket gslightlypveig-g siz'e',jt he jacket is loose and wrinklingfbecomesevenmore Because of these andjotheir application of pl'asticjackets *by -*'conventional 'extiusis joperationstostrip-woundinte rlock has" sometimes adopted the: on e [procedure 7 of;

tions move toward each otheron the concave sideof the thermoplastic, i a ctcr, is caused to1se't as promptly? V i s ib i i lf'fll extrusion operation. For example, the hose with the freshly ;.ext ruded qjacket, 'thereonz-is 'tlt bduc ed immediately intggaj-coolinfg sightly arid objectionable when the'hose" is bent;

'fliculties inciderit th vtblowin g on the. jacket-l rThis 'pro durefinvolvesj:ex-

r ofthe apparatus shownin'FIG. 1;and

. 3 itself is free from the influence of any substantial tensile force. In this respect the new jacketed hose is distinctly superior to hose made by blowing on the jacket. The jacket of hose made in the latter fashion necessarily is under a substantial hoop stress on the hose, in order to make sure that it fits the hose snugly and does not wrinkle when the hose is bent. Because it is under a hoop stress, however, the edges of any cut which is made in it immediately pull apart, and there is always some tendency for a cut to run along the hose. Moreover, unlike hose having a jacket applied by a conventional extrusion operation, the new hose is characterized by there being no interpenetration of the plastic jacket material into the interstices between convolutions of the hose. Hence the jacket material of the new hose does not limit the extent to which adjacent convolutions may move relative to each other; and so limit the flexibility of the hose. Furthermore, the new hose in the unbe'nt condition with its axis substantially straight has all its convolutions in the first position described above,'that is,

all convolutions are compressed as close together as pos-' sible, each convolution being in direct contact with adjoining convolutions completely about the circumference of the hose. Hence when the hose isbent, adjacent convolutions can move only away from each other on the outside of the bend, and wrinkling of the jacket due to movement of convolutions toward each other is prevented.

An advantageous embodiment of the invention is described below with reference to the accompanying drawings, in which:

FIG. 1 illustrates schematically an assembly'of apparatus suitable for making the hose of the invention;

FIG. 2 is a detail, partly in cross section, of flexible metal hose with the convolutions thereof spaced apart, or

opened, as they are likely to beupon being initially fed to the apparatus of-FIG. 1;

FIG. 3;is a view, on an enlarged scale, of theportion of the apparatus shown inFIG. 1 which serves to close the convolutions of the hose;

FIG. 4 is across section through the; extrusion head ,FIG. 5 is a;view,,partly in-cross section, of the-jacketed hose of ;the invention.

The apparatus shown in FIG. 1 comprises. an extrusion; apparatus to whichand throughwhich metalhose ll tobe jacketedrisfed by a pushing-device 12. The metal; hose is carried: on a supply. reeli13, from which itjis drawn by acooperating pair of convolution.- closing rolls 14 and 14a.

The metal'hose 11 is shownin the drawingsasconventional strip-wound interlocked ,rnetalqhose. However, it may ,equally well be strip-wound square. locked metal hose-(inwhich the side edges: of each convolution are bent through only about.90 instead of 180), or any othertype of strip-wound flexible metal hose. The hose, as his coiled onthe supplyreel"13,.and particularly as it" is .drawntherefrorn, is likely to be stretched'out sopthat its convolutions 15 (FIG- 2) are opened, i.e.

spacedapart sothat'the interstices lfi' between them are as wideaas the construction of the hose permits. The:

rolls 14.and 14a (whichare shown on an enlarged scale in FIG. 3) rotate in the direction indicated by the arrows,

ofa section regardless ofminor variations in base diameter along 1 its length, butwith'out being under any noticeable hoop.

and their supporting shafts 17 are geared or oth'erwise connected together so that they rotateat the samespeed;

They are preferably grooved peripherall'y on a radius oft curvature equalto the radius of'the metal hose, and

the grooves" advantageously are lined with rubber-for ofthe hose. Moreover, with thehose straightlfit other soft friction material-J The rolls grip the-hose gently but; with; sutiic ientsforcei'toj draw the 'supply reel 13,f and advance ittoward .theiptrsh'in g devicellzf l The '1 rate atiji vhichj-the 14d ,rotate l jis high enough sojthat they tend toadvance the hose-toward the pushing device v 12: :linear velocity considerably.

above that at which the pushing device itself advances the hose toward the extruder 10. As a result, the convolutions of the hose become fully closed, with the side edges of each convolution in direct contact with adjoining convolutions throughout the entire circumference of the hose, as indicated at 18 in FIG. 3. Advantageously, the rolls rotate a little more rapidly than the rate at which the hose is permitted to advance by the pushing apparatus 12., so as to insure that all convolutions of the hose will be tightly closed when the hose arrives at the pushing apparatus. As a result, the rolls 14 and 14a slip somewhat on the hose 11 as they advance it toward the pushing device. In order to prevent the hose from buckling, it is fed from the rolls 14 to the pushing device 12 through a rigid guiding tube 19.

The pushing device 12 consists essentially of two or more cooperating pairs of rolls 2t) and Ztla. These rolls may advantageously be of the same design as the rolls 14. Each cooperating pair of rolls 2t) and 20a is geared or otherwise connected together to insure that they rotate at the same speed, and all pairs of rolls are similarly connected, and for the same purpose, as by a sprocket chain 21. The multiple pairs of rolls in the pushing device 12 grip the hose with considerably greater aggregate frictional force than does the single pair of convolution-closing rolls 14. Hence the latter do not serve to push the hose forward any more rapidly than the rolls of the pushing device 12 permit. These latter rolls are rotated at the velocity required to advance the hose, with its convolutions maintained fully closed, at the desired velocity through the extrusion apparatus 10. A rigid guiding tube 22 receives the hose as it leaves the pushing device 12, to prevent it from buckling and to insure that its axis is kept straight in its passage to and through the extruding apparatus.

The extruding apparatus 10 is itself of conventional construction. Thermoplastic or other plastic material to be extruded about the hose (such, for example, as vinyl chloride polymer, polyethylene, a rubber composition, or the'like) is fed into the apparatus through a. feed hopper 23. This material, heated suflicie'ntly to be in a readily deformable plastic state, is forced under pressure out througha cylindrical extrusion die 24 inth'e extrusion head of the apparatus. shown in sectionand on an enlarged scale in FIG. 4. The;cylindrical aperture 24a of the extrusion die is slightly greater-in inside diameter than the outside diameter of the metal hose 11; The linear velocity at which the plastic material is extruded through the annular die opening 2421 is a little less than the linear velocity with which thetube 11, with its convolutions fully c1osed,is

passedthrough anaxial opening'in the extrusion die. 'At

a 'short distance out from the extrusion die, the extruded plastic jac'ket'26is brought snugly into engagement'with thetouter surface of the metal hose. Hence as the hose In this manner a jacket which fits the hose snugly,

" stress, is formed about the hose. At the sarnetirne the plastic material isk'ept from-penetratingto 'even a slight extent into the interstices be twcen adjacent convolutiohs volutions are fully closed; and the onl mpvemefi thecpnvolutions relative 'to one anotherwhich canp cur .istha't offseparation's alongjhe outside of the beiid e n :rnovenient of convolutions toward each "other onjth I "inside fthe' bend can occiir,; andth ereby wrinklingrof, l

'the jacket whenthe'hose is bent is pievented. I l

.Promptly after formation of the. extruded jacket 26, the hhse is delivered into a cooling vessel Zip/herein The extrusion die is ing force applied to it by the pushing device 12, so that no substantial tensile force or bending is imposed upon it until the jacket material has been congealed or set.

The slight degree of bending required for the hose to settle to the bottom of the cooling vessel 27 (which degree of bending is exaggerated in FIG. 1) is not great enough to have any deleterious effect on the jacket. Thereafter, the hose passes around a capstan 29 which is rotated at a velocity just sufficient to take it from the cooling vessel at the same rate that it is advanced therethrough by the pushing device 12. From the capstan, the jacketed hose is conveyed to apparatus (not shown) by which it is wound into coils or on to reels.

Jacketed hose prepared in the manner described above is illustrated, partially in cross section, in FIG. 5. 'In the completed hose, the frictional engagement of the jacket 26 with the hose holds the convolutions l5 closed, with their side edges in contact all around the circumference of the hose, in the same position in which they were advanced through the extruding apparatus, so long as the hose is straight. However, the ability of the hose to flex is not thereby impaired. Bending the hose simply causes the convolutions to open on the convex side of the bend, and to stretch the thermoplastic material correspondingly. There is and can be no movement of adjacent convolutions toward each other on the concave side of the bend, with attendant compression and wrinkling of the jacket material. Hence the hose when bent preserves the same smooth and unwrinkled appearance it has when straight. When the hose is straightened again, the adjacent convolutions are returned to the closed position shown in FIG. 5 and the stretched thermoplastic jacket contracts again. Thus the jacket remains free of objectionable wrinkles whether or not the hose is bent. It will be noted that the jacket 26 forms a smooth cylindrical outer layer which does not interpenetrate the hose convolutions and which thus does not It is of course apparent that jacketed hose may be made in accordance with the invention in any length for which the metal hose itself is available. Such hose is well protected against leakage, in or out, of moisture or other liquids, for the jacket is itself a seamless liquidand gas-tight tubing. At the same time, the hose has the mechanical ruggedness of the strip-wound metal hose itself, and it is as flexible as the metal hose used in its manufacture.

Jacketed strip-wound metal hose made as herein described may be used with great advantage as flexible electrical wiring conduit in regions where a moisture proof but flexible conduit is required. Many other uses will also suggest themselves to those skilled in the art.

I claim:

1. Jacketed strip-wound flexible metal hose having axially interlocking helical convolutions in which each convolution is movable relative to adjoining convolutions axially of the hose through the interlock between a first position in which adjoining convolutions are in direct contact with one another and a second position in which adjoning convolutions are spaced a substantial distance apart, and a seamless jacket of plastic material fitting snugly about the outer surface of said hose but free from any noticeable hoop stress when the hose is free from the influence of any substantial tensile force, said hose in the unbent condition with its axis substantially straight having the convolutions held in said first position by frctional engagement therewth of the jacket without any penetration of the jacket material between said convolutions, whereby when the jacketed hose is bent adjacent convolutions can move only away from each other on the outside of the bend and wrinkling of the jacket due to movement of convolutions toward each other on the inside of the bend is prevented.

; ZJJacketed strip-wound flexible metal hose having axially interlocking helical convolutions in which each conpresent any obstacle to the movement of the convolutions toward and away from each other.

A feature of the hose'produced as described above is that the jacket fits snugly about the outer surface of the metal hose throughout the enire length of the hose, regardless of minor commercial manufacuring variations in the hose diameter. At the same time, the jacket is free from any noticeable hoop stress throughout the entire length of the hose. The jacket therefore does not bunch or wrinkle; yet neither do the edges of any cut that may inadvertently be made in the jacket tend to pull apart and thus tend remake the cut runlengthwise of the hose.

The hose thus retains a neat and attractive appearance.

under all conditions of use, and injury to the jacket does not tend to be self-propagated, or to enlarge in any way.

volution is movable relative to adjoining convolutions axially of the hose through the interlock between a first position in which adjoiningconvolutions are in direct contact with one another and a second position in which adjoining convolutions are spaced a substantial distance apart, and a seamless jacket of plastic material fitting snugly about the outer surface of said hose but free from any noticeable hoop stress when the hose is free from the influence of any substantial tensile force, saidhose in the unbent condition with its axis substantially straight having the convolutions held in said first position by frictional engagement therewith of the jacket, whereby when the jacketed hose is bent adjacent convolutions can move only away from each other on the outside of the bend and wrinkling of the jacket due to movement of convolutions towardeach other on the'inside of the bend is prevented. Y

. References Cited in the file of this patent UNITED STATES PATENTS 2,045,540 Debenedetti June 23,1936

- FOREIGN PATENTS? 7 Blake June 23, 1931 

1. JACKETED STRIP-WOUND FLEXIBLE METAL HOSE HAVING AXIALLY INTERLOCKING HELICAL CONVOLUTIONS IN WHICH EACH CONVOLUTION IS MOVABLE RELATIVE TO ADJOINING CONVOLUTIONS AXIALLY OF THE HOSE THROUGH THE INTERLOCK BETWEEN A FIRST POSITION IN WHICH ADJOINING CONVOLUTIONS ARE IN DIRECT CONTACT WITH ONE ANOTHER AND A SECOND POSITION IN WHICH ADJOINING CONVOLUTIONS ARE SPACED A SUBSTANTIAL DISTANCE APART, AND A SEAMLESS JACKET OF PLASTIC MATERIAL FITTING SNUGLY ABOUT THE OUTER SURFACE OF SAID HOSE BUT FREE FROM ANY NOTICEABLE HOOP STRESS WHEN THE HOSE IS FREE FROM THE INFLUENCE OF ANY SUBSTANTIAL TENSILE FORCE, SAID HOSE IN THE UNBENT CONDITION WITH ITS AXIS SUBSTANTIALLY STRAIGHT HAVING THE CONVOLUTIONS HELD IN SAID FIRST POSITION BY FRICTIONAL ENGAGEMENT THEREWITH OF THE JACKET WITHOUT ANY PENETRATION OF THE JACKET MATERIAL BETWEEN SAID CONVOLUTIONS, WHEREBY WHEN THE JACKETED HOSE IS BENT ADJACENT CONVOLUTIONS CAN MOVE ONLY AWAY FROM EACH OTHER ON THE OUTSIDE OF THE BEND AND WRINKLING OF THE JACKET DUE TO MOVEMENT OF CONVOLUTIONS TOWARD EACH OTHER ON THE INSIDE OF THE BEND IS PREVENTED. 